Mayor Ed Lee, center, and members of the Board of Supervisors are joined by business, labor and community groups Tuesday to announce a ballot measure to raise the minimum wage.

As cities across the nation debate boosting pay for the lowest-paid workers, San Francisco proposed Tuesday hiking its minimum wage to $15 by July 2018 in what would preserve The City's standing as having the highest hourly minimum pay in the nation.

Mayor Ed Lee, who has faced criticism for the growing income inequality in the technology-fueled local economy, announced the November ballot measure Tuesday with the support of business and labor leaders as well as the Board of Supervisors.

"Our city has become more expensive. Working families, particularly those who earn minimum wage, are struggling," Lee said. "Today the current minimum wage at $10.74 ... just doesn't cut it. That's not enough."

Under the measure, the minimum wage would rise May 1, 2015, to $12.25 per hour and rise gradually each year until it hits $15 on July 1, 2018. Subsequently the wage would be increased according to the consumer price index.

"It will be in fact the highest minimum wage in the country," Lee said. Seattle recently passed a $15 minimum wage that will be phased in over seven years and includes several exceptions.

The mayor's proposal is a compromise in that he has persuaded Service Employees International Union Local 1021 and other community advocates to drop their previously proposed November ballot measure that would have increased the minimum wage at a faster rate.

Small-business advocate Scott Hauge, who was part of the talks, said the compromise will still be a "tough row to hoe" for many businesses, but, "You got to be a political realist."

Supervisor Jane Kim, who helped negotiate the deal as talks stretched into Monday night, said, "San Francisco is yet again setting the bar for workers' rights."

"We have been seeing a widening income gap between our lowest-paid workers and our highest-paid workers," Kim said. "In times of economic prosperity, no one should be left behind."

The San Francisco Golden Gate Restaurant Association, which represents hundreds of restaurants, was critical that it doesn't include an exemption for tipped workers, credit for health and sick leave costs, and a longer period of phasing it in.

"We are disappointed that our concerns were not heard," said the association's executive director, Gwyneth Borden.

Shaw San Liu, an organizer for the Coalition for a Fair Economy, a coalition of groups advocating for the wage increase, said the increase is needed as "workers are falling behind when it comes to paying the rent, paying basic living expenses."